1. Field of the Invention
This invention relates generally to combination apparatus for ejecting or expelling fluid and more particularly relates to the combination of a plungerless syringe for expelling or injecting a fluid in a substantially bubbleless manner thereby substantially eliminating the threat of an air-embolism and an injector, injector holder or ejection force applying means for applying fluid ejection force to a plungerless syringe. This invention also relates to an injector, injector holder or ejection force applying means for applying fluid ejection force to a plungerless syringe.
2. Description of the Prior Art
Syringes are well known to the art which include a substantially transparent plastic cylindrical tube providing a fluid receiving chamber, a plastic plunger mounted slidably in one end of the tube and a metal needle mounted to the other end of the tube. The plunger is withdrawn to create a vacuum and draw fluid into the chamber after which the plunger is forced into the chamber to expel or eject the fluid through the needle. Typically, the plunger and cylindrical member are disposable, but the metal needle typically is reusable and must be removed from the tube for resterilization prior to reuse. Removal of the needle is well known for the possibility of the user being pricked or stuck by the needle with the highly undesirable attendant possibility of infectious disease transmission.
Plungerless syringes are known to the art, such as for example the plungerless syringe disclosed in U.S. Pat. No. 5,102,398, entitled PLUNGERLESS SYRINGE, and patented Apr. 7, 1992, Barry L. Farris inventor. This plungerless syringe is disclosed as providing substantially bubbleless fluid ejection or expulsion by the employment of an air chamber attached to the bellows portion of the syringe and which air chamber is taught as being for entrapping air contained in the fluid.
As further known to those in the art, the plunger of the prior art plunger syringe, noted above, is initially partially depressed to expel some fluid from the syringe so as to purge air from the adapter or fluid delivery device, such as a needle or catheter, to which the syringe is connected thereby reducing, or substantially eliminating, the possibility of the injection of air into a person's blood stream with the attendant possible air embolism. The construction of the typical prior art plungerless syringe is such that it does not lend itself to two distinct stages of fluid expulsion including a first stage for ejecting or expelling a portion of the fluid in the syringe to purge air from the delivery system and a second stage for ejecting or expelling the remaining fluid contained in the syringe.
Accordingly, there exists a need for a plungerless syringe providing for two stages of collapse, an initial or purge stage where air contained in the fluid delivery device to which the syringe is attached is purged, and a second flush stage where the remaining fluid in the syringe is expelled.
The prior art plunger syringe, noted above, is also used to determine whether the needle has been properly inserted into a blood vessel of a patient. This is accomplished by partially depressing the plunger to expel a portion of the fluid contained in the syringe after which the plunger is withdrawn to reflux the previously expelled fluid and to withdraw a blood sample into the transparent syringe which provides a visible determination that the tip of the needle is in fact in a blood vessel. The plungerless syringes known to the prior art do not include any structure permitting such fluid reflux and blood sample withdrawal and hence cannot be used to determine if the needle tip is properly inserted into a blood vessel.
Accordingly, there exists a need for a plungerless syringe provided with structure permitting the reflux of previously expelled fluid and a blood sample to determine whether the tip of the needle attached to the plungerless syringe is properly inserted into a blood vessel.
Still further, the typical prior art plunger syringe is relatively expensive to manufacture because it must be manufactured in several steps and assembled and frequently lubrication is required.
Accordingly, there exists a need in the art for a plungerless syringe which is relatively inexpensive to manufacture, contains no moving parts making the plungerless syringe suitable for radiation and sterilization.
Injectors or injector holders are known to the art for facilitating the operation of syringes provided with a plunger.
Although plungerless syringes can be operated directly by a user as illustrated in FIG. 4 and described below, it has been found that it can be beneficial to the user to provide an injector or injector holder for facilitating operation of a plungerless syringe.
Accordingly, there exists a need in the art for combination plungerless syringe and injector or injector holder and a need in the art for an injector or injector holder for facilitating operation of a plungerless syringe.